We report a case of salivary gland neoplasm and associated hepatoblastoma.
The sialoblastoma was diagnosed by prenatal sonography; however, the
hepatoblastoma was imaged post-operatively. Prior knowledge could have
prevented a subsequent operation, including the additional risks of
repeat anesthesia.

We suggest that if a sialoblastoma is in the differential diagnosis,
then additional imaging may be indicated because of the possibility
of associated lesions.

Department of Radiology, Mount Sinai School of Medicine of the City
University of New York, NY 10029, USA.

AJNR Am J Neuroradiol 1997 May;18(5):847-50 Abstract quote

We report the findings in a 21-month-old girl who had a noninfiltrating
mass in the left cheek, just anterior to the masseter muscle, which,
at surgery, proved to be a sialoblastoma. Sialoblastoma has a histologic
appearance reminiscent of a primitive state of salivary gland development;
that is, it shows an arrested state of salivary maturation.

MR imaging in this case showed that the lesion was isointense with
muscle on T1-weighted images, had a high-intermediate signal intensity
similar to that of fat on T2-weighted images, and enhanced sparsely
and nonhomogeneously.

GROSS APPEARANCE/
CLINICAL VARIANTS

CHARACTERIZATION

GENERAL

Sialoblastoma: a clinicopathologic and immunohistochemical study of 7 cases.

Sialoblastoma is a rare congenital or perinatal salivary tumor that varies in histologic features and biologic potential. Seven cases from the files of the Armed Forces Institute of Pathology are presented.

These tumors occurred in 4 males and 3 females with ages ranging from prenatal to 6 months at the time of discovery. Five lesions originated from the parotid gland; 2 lesions were from the submandibular gland. All lesions presented as nodular to multinodular swellings and ranged in size from 2.0 to 7.0 cm. The principal sign or symptom was rapid growth.

Two histologic patterns with differing behavior predominated: (1) a favorable pattern had semiencapsulation of cytologically benign basaloid tumor cells with intervening stroma; and (2) an unfavorable histology of anaplastic basaloid tumor cells, minimal stroma, and broad pushing to infiltrative periphery. Four and three tumors had favorable and unfavorable growth patterns, respectively. One unfavorable lesion had vascular invasion, and another demonstrated perineural invasion. All 3 tumors with unfavorable histology recurred.

Tumor cells in 3 cases were immunohistochemically reactive for keratin, S-100, smooth muscle actin, and calponin to varying degrees. All 3 tumors were reactive for p63. alpha-Fetoprotein was expressed in 2 unfavorable tumors. Ki67 was expressed at 3% in a favorable tumor and 40% and 80% in the 2 unfavorable lesions. Treatment involved surgical excision. One patient received adjuvant chemotherapy. Two sialoblastomas resulted in recurrences within a year and another developed a recurrence after 4 years. One sialoblastoma developed lung metastasis within 1 month of the original biopsy.

Although a clinical correlation is suggested by a favorable/unfavorable histologic grading system the biologic behavior is nonetheless considered unpredictable.

Congenital tumours of the salivary gland: a case report and review.

Harris MD, McKeever P, Robertson JM.

Department of Histopathology, Peterborough District Hospital, UK.

Histopathology 1990 Aug;17(2):155-7 Abstract quote

A congenital epithelial tumour of the submandibular salivary gland,
occurring in a child of 10 months, is described. The lesion appeared
benign and consisted of basal type cells, showing ductal and acinar
differentiation with myoepithelial cells. The associated fibrous stroma
contained blood vessels and small nerve bundles. A few similar lesions
have been reported in the past, some of which showed features of malignancy.

Although various names have been proposed, we suggest that these lesions
represent a single group derived from a primitive cell line and advocate
the use of the term sialoblastoma.

There are four clinicopathologic categories of the exclusively major
salivary gland tumors that present in the perinatal period. The two
with the smallest representation among the 20 cases reported to date
are those with a hamartomalike appearance and those with benign adult
equivalents--the pleomorphic and monomorphic adenomas. Five cases have
been undifferentiated or basaloid salivary carcinomas. Embryomas (sialoblastomas)
are the most numerous.

These tumors manifest a histologic phenotype like that of the epithelial
anlage of the salivary glands, albeit in an arrested state of differentiation.

VARIANTS

SUBMANDIBULAR GLAND

Sialoblastoma of the submandibular gland: report of a case and
review of the literature.

Sialoblastomas are rare perinatal epithelial salivary tumors, with
only 22 reported cases in the literature. While they have been reported
to occur predominantly in the parotid gland, we present one case of
sialoblastoma of submandibular gland origin. The surgical management
of this patient is discussed.

Department of Otolaryngology, Mount Sinai School of Medicine, City
University of New York, New York 10021, USA.

Am J Surg Pathol 1999 Mar;23(3):342-8 Abstract quote

Sialoblastoma is an extremely rare salivary tumor diagnosed at birth
or shortly thereafter with significant variability in histologic range
and clinical course, so that for an individual case it may be difficult
to predict the most appropriate therapy.

We detail the case of a toddler noted to have a firm 1-2-cm mass in
the left cheek at 21 months. Parotidectomy was performed at 26 months,
revealing a sialoblastoma; the resection margins were positive. During
the next 10 months, the mass recurred or persisted, necessitating numerous
procedures. The tumor was composed of basaloid cells with fine chromatin
and other more mature cuboidal epithelial cells. Ductules and solid
organoid nests with some tendency toward peripheral pallisading were
also noted. There was no perineural invasion; necrosis initially was
sparse but increased over time. The mitotic rate also increased from
6 to 7/10 high-power fields in the first resection to 20/10 high-power
fields in the last resection. Nuclear pleomorphism increased with time.
The MiB1 proliferative index revealed a dramatic increase in the number
of labeled nuclei: from 3 cells/10 high-power fields in the first specimen
to 94 cells/10 high-power fields for the last specimen. Cytokeratin
accentuated the ductal structures. S-100 showed a diffuse staining pattern,
with darker staining of the spindled myoepithelial cells. The Her-2-neu
protein showed moderate cytoplasmic staining, whereas the p53 showed
only occasional labeling of nuclei.

This is the first case of sialoblastoma with evidence of increasing
anaplasia based on increasing proliferative capacity. Therefore, the
distinction between benign and malignant sialoblastomas may not be as
well defined as previously thought. The patient's prognosis is likely
to be determined by the tumor grade as well as the stage at presentation
and the extent of resection.

SPECIAL STAINS/
IMMUNOPEROXIDASE/
OTHER

CHARACTERIZATION

SPECIAL STAINS

IMMUNOPEROXIDASE

Sialoblastoma: a case report and review of the literature on congenital
epithelial tumors of salivary gland origin.

The histologic, immunohistochemical, and ultrastructural features of
a congenital epithelial tumor of the parotid were studied.

The tumor was characterized by solid nests of epithelial cells intermingled
with proliferating ductal structures lined by a double layer of cells.
Immunoperoxidase staining for cytokeratin, vimentin, actin, and S-100
protein showed the presence of cytokeratin in the ductal cells as well
as the presence of vimentin, actin, and S-100 protein in the outermost
layer of the ducts. The solid nests were focally reactive to S-100 and
vimentin.

The term "sialoblastoma" is favored. Review of the literature on congenital,
epithelial salivary gland tumors showed that a few cases recurred locally
and only one case had regional lymph node involvement. No distant metastasis
has been reported.

Congenital epithelial tumours of the salivary glands are very rare.
The Salivary Gland Registry maintained in the Department of Pathology.
University of Hamburg, contains only three cases among a total of 6,646
salivary gland tumours from the years 1965-1994. The three cases were
classified as congenital basal cell adenoma, two of the parotid gland
and one of the submandibular gland.

Histologically, the three adenomas were similar in structure to the
adult counterpart of basal cell adenoma with solid, trabecular or tubular
(duct-like) patterns. In some cystic spaces of the duct-like structures
PAS- and Astra blue-positive substances were secreted. On immunocytochemistry,
the luminal duct-like cells showed membranous expression of cytokeratins
3, 5, 6, 7, 13 and 19. In the isomorphic basaloid cells of the solid
and trabecular cell nests few cells expressed cytokeratin. On the outside
of the solid cell nests there were smaller elongated myoepithelial-like
cells, which expressed cytokeratin 14 and vimentin. Cytokeratins 1,
2, 4 and 18 were not expressed. The pattern of expression reflects the
different stages of maturity of the tumour cells and is related to the
development of the salivary glands until the end of the 3rd embryonal
month with an arrest of further cell differentiation. No acinic cells,
invasive growth, recurrence or metastases were observed.

The natural history of a rare parotid tumor, the sialoblastoma (embryoma)
is reported. It is a blastematous neoplasm said to recapitulate the
epithelial differentiation of a gland at various stages of development.
The tumor grew in a period of 5 years (from shortly after birth until
it was excised) to a firm asymptomatic mass measuring 5 cm in greatest
diameter.

With a diagnosis of adenoid cystic carcinoma (a common misdiagnosis),
the patient was referred to the reporting institution, where the diagnosis
was revised. Five months later, completion parotidectomy for presumed
recurrence failed to demonstrate residual tumor. One year later, the
patient appears to be free of disease. The authors propose that sialoblastomas
should be regarded neither as benign nor malignant, but as one single
disease with local infiltrative potential.

Based on this concept, sialoblastomas can be treated with early conservative
surgery alone, provided that free margins are obtained.